import com.Wu.DBUtil;
import com.Wu.product.model.Product;
import com.Wu.product.service.ProductService;
import com.google.gson.Gson;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.*;
import java.util.ArrayList;

//@WebServlet("/product_list.do")
public class ProductListServlet extends HttpServlet {


    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.获取数据库连接
        Connection conn = DBUtil.getConnection();
        if (conn == null) {
            System.out.println("数据库连接获取失败！");
        } else {
            System.out.println("数据库连接获取成功！");
        }
        //2.准备SQL
        String sql = "select * from tb_product order by create_time desc limit 10";
        //3.声明操作对象
        PreparedStatement ps = null;
        //4.声明结果集对象
        ResultSet rs = null;
        try {
            //5.获取操作对象
            ps = conn.prepareStatement(sql);
            //6.执行SQL并返回结果集
            rs = ps.executeQuery();
            //使用List来存储商品信息
            ArrayList list = new ArrayList();
            //7.解析结果集
            while (rs.next()) {
                //创建商品对象
                model product = new model();
                product.setDescription(rs.getString("description"));
                product.setName(rs.getString("name"));
                product.setId(rs.getInt("id"));
                product.setMarket_price(rs.getDouble("market_price"));
                product.setSell_price(rs.getDouble("sell_price"));
                product.setPicture(rs.getString("picture"));
                //将商品信息添加到list中
                list.add(product);
                //将对象置为空，让GC尽快回收相关的内存
                product = null;
            }

            //9.将List对象转为JSON格式字符串
            Gson gson = new Gson();
            String result = gson.toJson(list);
            //10.获取输出流
            //10.1 设置响应的内容类型
            resp.setContentType("application/json");
            //10.2 设置响应的数据编码格式
            resp.setCharacterEncoding("utf-8");
            //10.3 输出响应数据
            resp.getWriter().print(result);

        }catch (SQLException e){
            throw new RuntimeException(e);
        }
        //8.关闭资源
        DBUtil.closeResource(conn,ps,rs);
    }
}